Saturday, April 6, 2013

Does Vitamin D Deficiency Raise Autism Risk?

States bathed in the most ultraviolet B rays have three times fewer cases of autism than those with the least UVB exposure, according to research published in the December issue of the journal Dermato-Endocrinology. The study is the latest to link the "sunshine vitamin" D, which is produced in the skin when exposed to UVB rays, to autism spectrum disorders, which impact 1 in 88 U.S. children.
Its authors suggest the autism epidemic could be curbed if more pregnant mothers and infants had healthy vitamin D levels. We interviewed study co-author John Cannell, MD, founder of the nonprofit Vitamin D Council:Natural Foods Merchandiser: When did you start suspecting a link between vitamin D and autism?John Cannell: In 2007, I realized a profound change had taken place when it came to weaning. Instead of moving their children to D-fortified cow’s milk, many parents were weaning their children on juice and other beverages. Meanwhile, mothers today protect their babies’ skin by avoiding sun or putting on sunblock. Vitamin D is crucial for brain and immune system development, yet once they are weaned, many babies have no source of solar or dietary vitamin D. I thought, might that help explain why the incidence of autism has flared up? I published the idea in the journal Medical Hypothesis in 2008.NFM: What has research shown since?JC: Five studies (from groups around the world) have shown that vitamin D deficiency is high among autistic children. One study showed that the higher the vitamin D level, the less severe the autism (and vice-versa).NFM: If mom lacks D while pregnant, is her child at risk?JC: Researchers have yet to look specifically at vitamin D levels of a large group of autistic children and D levels of their mothers while pregnant. However, a number have looked at maternal D levels and childhood development. One Spanish study looked at psychological development in 4-year-olds and then looked at mom’s vitamin D levels when pregnant. It found a direct relationship between D deficiency and abnormalities in psychological development. Another Australian study found that the lower the mom's D levels during pregnancy, the more likely the child was to have speech difficulties.NFM: How did you do your latest study?JC: We obtained surface UVB readings from around the country and state-by-state incidence of autism from the U.S. government and correlated the two. We controlled for age, race, dietary considerations and other factors.What did you find? JC: The higher the vitamin D-producing UV radiation in a state, the lower the incidence of autism. Arizona has three times less autism than Maine. This is the first time there has been such a clear association shown between autism and surface UVB radiation.NFM: How might lack of vitamin D be a risk factor for autism?JC:Autoimmune disorders (which some research suggests autism is among) start with a dysfunctional immune system, followed by a trigger (a fever, allergy, vaccine). The lack of vitamin D (either in utero or after weaning) causes a dysfunctional immune system, leaving the child prone to such disorders.NFM: This science is young. Are there other reasons for pregnant moms to take D?JC: There have been randomized controlled trials that have shown that 4,000 International Units per day can prevent C-section, pre-eclampsia, low birth weight, maternal infection and many other problems.NFM: What should parents do?JC: Modern humans simply cannot get enough D-producing UVB radiation. Mom should take adequate amounts of D before she even plans to conceive a child—5,000 IU per day—and continue during pregnancy and while breastfeeding. If she is not taking that amount, the breastfeeding infant should take 1,000 IUs daily. Formula-fed infants need an extra 600 IUs daily. Once weaned, the infant needs to take vitamin D—1,000 IUs per day for under 25 pounds; 2,000 IUs for up to 50; and 3,000 for 50 to 75 pounds.